Toward understanding rich superclusters.

Substructure and galaxy content.

ApJ, accepted

M. Einasto, E. Saar, V. J. Martinez, J. Einasto, L. J. Liivamägi, E. Tago, J.-L. Starck, V. Müller, P. Heinämäki, P. Nurmi, S. Paredes, M. Gramann and G. Hütsi

We present a morphological study of the two richest superclusters from the 2dF Galaxy Redshift Survey (SCL126, the Sloan Great Wall, and SCL9, the Sculptor supercluster). We use Minkowski functionals, shapefinders, and galaxy group information to study the substructure of these superclusters as formed by different populations of galaxies. We compare the properties of grouped and isolated galaxies in the core region and in the outskirts of superclusters. The fourth Minkowski functional $V_3$ and the morphological signature K1-K_2 show a crossover from low-density morphology (outskirts of supercluster) to high- density morphology (core of supercluster) at mass fraction approximately 0.7. The galaxy content of supercluster cores and outskirts are different. This suggest that both local (group/cluster) and global (supercluster) environments are important in forming galaxy morphologies and determining the star formation activity. We show that there are substantial differences between the two superclusters we studied, both in their overall morphology and galaxy content, and in their fine structure as delineated by galaxies from different populations. The differences between the superclusters indicate that these superclusters have different evolutional histories.

The luminosity density field of 2dF redshift survey:

Northern sky, SCL126 at distance of about 250 Mpc

Southern sky, SCL9 at distance of about 300 Mpc

The richest superclusters from the 2dF redshift survey, the density field view:

SCL126 ( mpg movie );

SCL9 ( mpg movie );

The sky distribution of galaxies in superclusters SCl126 and SCL9:

SCL126

SCL9

D1 - core of supercluster, D2 - outskirts. Red points: galaxies with red colours and spectra typical to late type galaxies. Blue points: blue galaxies with spectra typical to early type galaxies.

Paper: rich2.pdf

Minkowski functionals for rich superclusters.

Additional reading:

E. Saar "Multiscale methods".

J. M. Bernardo "Model-free objective Bayesian prediction".

The R Project for Statistical Computing.

Wand, M. p. and Jones, M.C. "Kernel Smoothing", Chapman & Hall, London, 1995

 

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